The annual cycle of riverine influence in the eastern Gulf of Mexico basin

Morey, Steven L.; Schroeder, William W.; O’Brien, James J.; Zavala‐Hidalgo, Jorge

doi:10.1029/2003gl017348

Cited by 80 publications

(71 citation statements)

References 11 publications

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“…Mississippi River plume in summer. This region is associated with the southeastward flow of the Mississippi River plume observed in July to August caused by the eastward component of the winds, which displaces the riverine nutrientrich waters offshore during this period (Gilbes et al 1996;Morey et al 2003aMorey et al , b, 2005. Region 6.…”

Section: Region 3 the Southern Inner-intermediate West Floridamentioning

confidence: 97%

Regionalization of the Gulf of Mexico from space-time chlorophyll-a concentration variability

et al. 2010

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Regions in the Gulf of Mexico are determined based on the statistical behavior of the long-term monthly means of chlorophyll-a concentration from SeaWiFS satellite estimations. An analysis based on the four largest modes of an empirical orthogonal decomposition, which account for 84.9% of the variance, results in nine spatial patterns with different statistical behavior representing 14 connected regions. The time evolution (or principal component) of the first two modes resemble the annual cycle, but each one with a different phase; the third mode represents a semiannual period and the fourth mode shows three maxima and minima. A map of the resulting regions is obtained and the oceanographic processes taking place in each region are discussed. The largest region covers most of the deep Gulf and the continental slope. Other regions in the deep Gulf are located southeast of the Mississippi River mouth and off-shelf of southern Texas and Tabasco, all associated with seasonal offshore cross-shelf transports. The shelves are associated with specific regions, but in wide shelves the inner and outer continental platforms are separated. Among the causes that determine different regions are topographic characteristics and the seasonal variability of physical processes, mainly entrainment caused by heat and momentum fluxes, upwelling, river plumes, and cross-shelf transports associated with the convergence of the along-coast currents.

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Section: Region 3 the Southern Inner-intermediate West Floridamentioning

confidence: 97%

Regionalization of the Gulf of Mexico from space-time chlorophyll-a concentration variability

et al. 2010

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“…From left to right: t Uwind only ( Figures 1a-1d); F May + t Uwind (Figures 1e-1h); F spring + t Uwind (Figures 1i-1l); F 11 + t Uwind (Figures 1m-1p); May-June NO 3+2 + t Uwind (Figures 1q-1t); May NO 3+2 + t Uwind (Figures 1u-1x). et al, 2011], a persistent west wind reduces the areal extent by ultimately moving the river plume offshore, away from the continental shelf and into deep water [Lentz, 2004;Morey et al, 2003aMorey et al, , 2003bSchiller et al, 2011]. This movement removes the two factors necessary for coastal ocean hypoxia formation: nutrient supply and density stratification.…”

Section: Discussionmentioning

confidence: 99%

Relative role of wind forcing and riverine nutrient input on the extent of hypoxia in the northern Gulf of Mexico

Feng¹,

DiMarco

Jackson

2012

Geophysical Research Letters

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[1] Seasonal hypoxia of the northern Gulf of Mexico has been observed for more than 25 years. It is generally accepted that the variation in the areal extent of hypoxia is determined by changes in nutrient addition from the Mississippi River. In this study, we investigate the statistical relation between the hypoxic area and a new variable, the duration of west wind, using the available measurements for the period 1985-2010. Special consideration was paid to the 1993-2010 period, a time when a large shift in the seasonal hypoxia pattern has been reported. When excluding the years in which hurricanes directly impacted the hypoxic area observation, we find that the duration of west wind is correlated with the hypoxic area at r 2 = 0.32 for the 1985-2010 period, and r 2 = 0.52 for the 1993-2010 period. Multilinear regressions using both wind duration and May-June nitrate loading improve the statistical relationships for both periods to r 2 = 0.69 and 0.74 for the long and short time periods, respectively. Mechanistically, the statistical relationships reflect the movement and changes in horizontal river plume position associated with the wind and the influence of stratification on the hypoxic area. Citation: Feng, Y., S. F. DiMarco, and G. A.Jackson (2012), Relative role of wind forcing and riverine nutrient input on the extent of hypoxia in the northern Gulf of Mexico, Geophys. Res. Lett., 39, L09601,

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“…When the LC is extended far to the north, these LCFEs can also interact with the MR plume. In particular, the proximity of an LCFE to the LC, or to a newly formed LC Eddy, is able to enhance the offshore export of MR waters (Walker et al , 2005Morey et al 2003b;Schiller et al 2011;Androulidakis and Kourafalou 2013;Schiller and Kourafalou 2014). Independent from the LC frontal dynamics, the Northern GoM continental shelf slope presents a rich eddy activity, marked by the presence of both cyclonic and anticyclonic eddies that may interact with the MR plume (Hamilton 1992;Hamilton et al 2002;Schiller et al 2011).…”

Section: Introductionmentioning

confidence: 96%

“…Another important mechanism forcing the MR plume is the interactions with deep GoM flows; this is corroborated by the very narrow continental shelf in the vicinity of the Mississippi Delta (Walker et al 2005;Morey et al 2003b;Schiller et al 2011). The deep GoM dynamics are dominated by the LC and the associated eddy field.…”

Section: Introductionmentioning

confidence: 97%

Mississippi waters reaching South Florida reefs under no flood conditions: synthesis of observing and modeling system findings

Hénaff

Kourafalou

2016

Ocean Dynamics

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In August 2014, in situ measurements revealed an intense salinity drop impacting South Florida coral reefs, between Pulley Ridge (Southwest Florida Shelf) and the Florida Keys. The low salinity waters had a surface signal of 32 (down from 35.2) and extended over a 15-20-m deep lens. Satellite observations showed that this abrupt drop in salinity was due to a southeastward export of Mississippi River waters from the Northern Gulf of Mexico (GoM), revealing strong interaction between coastal and oceanic flows. Unlike previous events of marked long-distance Mississippi water export, this episode is not associated with Mississippi flooding conditions, which makes it a unique study case. We have developed a highresolution (~2 km) comprehensive hydrodynamic numerical model of the GoM to study the conditions that controlled the 2014 Mississippi River water export episode. It is based on the Hybrid Coordinate Ocean Model (HYCOM) and assimilates remotely sensed altimetry and sea surface temperature observations, to ensure that the simulated upper-ocean is realistic.

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The annual cycle of riverine influence in the eastern Gulf of Mexico basin

Cited by 80 publications

References 11 publications

Regionalization of the Gulf of Mexico from space-time chlorophyll-a concentration variability

Regionalization of the Gulf of Mexico from space-time chlorophyll-a concentration variability

Relative role of wind forcing and riverine nutrient input on the extent of hypoxia in the northern Gulf of Mexico

Mississippi waters reaching South Florida reefs under no flood conditions: synthesis of observing and modeling system findings

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